Semiconductor industry relies on device scaling to deliver improved performance at lower costs. Flash memory is the mainstream non-volatile memory in today's market. However, Flash memory has a number of limitations that is posing a significant threat to continued advancement of memory technology. Therefore, the industry is exploring alternative memories to replace Flash memory. Contenders for future memory technology include magnetic storage random access memory (MRAM), ferroelectric RAM (FeRAM), and resistive switching memories such as phase change RAM (PCRAM), metal oxide based memories, and programmable metallization cell (PMC) or ionic memories. These memories are also called as emerging memories.
To be viable, the emerging memory has to be better than Flash memory in more than one of technology metrics such as scalability, performance, energy efficiency, On/Off ratio, operational temperature, CMOS compatibility, and reliability.
One of the challenges of memory design relates to cell margin. For example, the switching element, which switches between a first state and a second state has to maintain a sufficient difference between the two states so that a subsequent read operation may distinguish between them. If the difference between the two states becomes smaller than the sensitivity of the reading process, then the memory cell may lose the stored data.